Bob-Bob Hardyoyo
A small-time thief in Ankh-Morpork who was quite willing to do a mildly unpleasant job, no questions asked, for a man he met in a pub in exchange for a sum of money.
How was he to know that he was actually helping the Klatchian war effort? See Jingo for more details.
This kind of thing really depresses Sam Vimes.